Signaling apparatus for telephone-lines



(No Model.)

P. R. MGBERTY. SIGNALING APPARATUS FOR TELEPHONE LINES.

W M M I I I Patented June 30, 1896.

jibe

Wan/C 7%. J2 $7 EerZ Zlvzwe; as.

ANDREW BLRAHAMfHWO-LFHQWASHINGTON D C UNITED STATES PATENT OFFICE.

FRANK R. MCBERTY, OF DOYVNERS GROVE, ILLINOIS, ASSIGNOR TO THE \VESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS.

SIGNALING APPARATUS FOR TELEPHONE-LINES.

SPECIFICATION forming part of Letters Patent No. 562,906, dated June 30, 1896.

Application filed October 29, 1895. Serial No. 567,240. (No model.)

To all whom it may concern.- eXciting-current for the lamps, controlled by 50 Be it known that I, FRANK R. MGBERTY, the current in the line to the substation as a citizen of the United States, residing at determined by the use of the telephone there. Downers Grove, in the county of Du Page It consists in the connection with the line and State of Illinois, have invented a certain of a relay responding to currents in the line newanduseful Improvementin Signaling Apto the substation, and a local branch or re- 55 paratus for Telephone-Lines, (Case No. 31,) turn circuit of the line, of moderate resistof which the following is a full, clear, concise, ance, controlled by the relay; the other cirand exact description, reference being had to cuits remaining undisturbed, so that merely IO the accompanying drawing, forming apart of the addition to the line of the relay and the this specification. subsidiary circuit which it controls, in proper 60 My invention concerns signaling systems relation to the other apparatus, is required to for telephone-lines in which annunciators or permit the operation of lines of great resistresponsive instruments included in the line ance in a similar manner to that of lines of I 5 are operated by current derived from a source low resistance.

located at the central station. It applies par- I prefer to interpose the magnet of this re- 6 3 ticularly to lines of such high resistance as to lay directly in the line-circuit, the magnet beprevent the flow of suflicient current through ing shunted or practically short-circuited as the line for the proper excitement of the sigto telephonic currents by a non-inductive renaling instruments, its purpose being to prosistance-coil; and to provide a local branch vide an additional or subsidiary path conor return circuit for the line, having aresist- 7o trolled by the current to the substation, for ance about equal to that of ashort telephonepermitting the normal signal-exciting current line, including the switch-contacts of the to flow. relay.

2 5 In certain arrangements of telephone-lines, In the signaling system before alluded to,

small incandescent lamps are interposed in the line-signal, displayed in the act of bring- 75 the line-circuits to actas signals, being illumiing the station-telephone into use, is rendered nated by current from a central source iiowinoperative when connection is made with the ing through the lines to the substations while line in compliance with the call-signal, a

the telephones there are in use. This consupervisory or clearing-out signal bestitutes a satisfactory and effective mode of ing temporarily substituted for it adapted to So signaling, but its use in this simple form is light in response to the cessation of the curlimited to comparatively short lines of low rent in the line, that is, in response to the reresistance, since the provision of a source of turn of the station-telepl1one to its position current of sufficiently high electromotive of disuse. This supervisory signal also is of force to light the lamps in long lines is procourse subject in its use to the same restric- 8 5 hibited by various practical considerations. tions as to line-resistance as the line-signals. Nevertheless, the proportion of long and high The present invention permits the operation resistance lines in an exchange of ordinary of these signals also, independently of the re- 0 character is so small that this system of sigsistance of the line-circuit.

naling maybe economically applied in the ex- The invention is illustrated in the drawing 0 change, provided that some subsidiary or herewith in combination with a signaling sys auxiliary contrivance be furnished to permit tem of the type alluded to. The figure is a the operation of the lamps or other similar diagram of two line-circuits terminating in a signals in the long lines. It is to this phase telephone-switchboard furnished with line of the problem that the present invention is and supervisory signals and with switching 5 addressed. appliances, one of the lines, assumed to be of This invention aims, as before mentioned, high resistance, being equipped with the into provide a subsidiary path for the necessary vention.

At the substation are placed a receivingtelephone a and a transmitting-telephone a, a telephone-switch a a signal-bell a and a condenser a eluded permanentlyin the line-circuit 1 2, but the condenser obviously interrupts the line, so as to prevent the flow of continuous currents. The switch 61, controls the continuity of a bridge 3 of the line including the telephones.

At the central station the line conductors are extended to the poles of a source b of current, which may be common to the diiferent lines of the exchange, impedance-coils c and 0' being interposed in the lines near the battery b to prevent the shunting of telephonic currents through the battery.

A signal-lamp d is included in the line conductor 2, and located adjacent to the lamp is a spring-jack or connection terminal 6 connected as usual with the line conductors. The mode of operating these lamp-signals will be obvious. The removal of the receivingtelephone from its switch at a substation will, if the line be of low resistance, permit suflicient current to flow from battery I) through the line-circuit to illuminate the signal-lamp and thus to indicate the call.

It may be assumed that line to station Bis such a line of low resistance, but that line to station A is of such high resistance as to prevent the direct working of the signals inthis way. The invention is therefore applied to line to station A. This consists in a relay g, having its magnet interposed in line conductor2, or, preferably, in shunt of a non-inductive resistance-coil h directly in the line, and a bridge or return-circuit 4 between line conductors 1 and 2, controlled by the relay. This bridge includes a resistance or impedance coil 6, whose function is to prevent the short-circuiting of currents in the line.

The usual connecting-plugs k and 7c are furnished for uniting lines, connected by a plug-circuit 5 6. The conductors of the plugcircuit extend through the switch-contacts of the usual calling-key Z, and to the contacts of a listening-key m for connecting a telephone with the plug-circuit. The conductors include also the helices of a transformer 71, wire 5 extending through helices n and 01 and wire 6 through helices 91 01 The helices n and n are united through supervisory lamps 0 and 0'', which are associated with the corresponding plugs k and In shunt of lamps 0 and 0 are two local circuits containing non-inductive resistances p and p, and leading to a battery q. The united terminals of helices n and n are connected through wire 7 with one pole of battery I), and the point of junction of lamps o and 0 are connected through a wire 8 with the other pole of the same battery.

lVhile no part of the apparatus is in use the line-lamps cl are inert, the bridges 3 and The bell and condenser are in-- A of the line-circuits being interrupted, the former at the telephone-switch and the latter at the relay, in line to station A. The supervisory signals 0 and 0 are, however, lighted by current from battery q through the two too feeble to illuminate lamp d but sufficient to excite the relay g. The branch or return circuit A is thereby closed, whereby the current in the circuit from battery Z9 through wires 1 4: 2 is increased sufficiently to light the lamp and give the signal.

The insertion of plug 70 into spring-jack 6 brings portions of the conductors 5 and (3, including coils n and n of the transformer, into shunt of the portions of lines 1 and 2 leading to battery I), and, by diverting the current from these shunted conductors,brin gs about the extinguishment of line-lamp (i. At the same time the current from battery Z1, through wire 8, helix n of the induction-coil, conductor 6 of the plug-circuit, line-wire 2, and the return-circuit produces or tends to produce a condition of no potential difference between the terminals of lamp 0, so that this lamp also is extinguished. The lamps remain in this condition until the line-circuit is again interrupted at the substation by the replacement of the telephone on its switch. Then the relay g permits its switch-contacts to interrupt the bridge 4. The nul condition at the terminals of lamp 0 being thus disturbed, this lamp becomes lighted and gives its signal.

I do not deem it necessary to describe the operation of the signals of line to station 13, nor the process of actually making connection between the lines, since these will be obvious from the foregoing description.

I define my invention as follows:

1. The combination with a telephone-line having a switch at its substation controlling the continuity of the line, and a signaling instrument and source of current in the line. of a subsidiary bridge or return circuit of the line between the signaling instrument and the substation, and means for controlling the continuity of the bridge from the substation, as described.

2. The combination with a telephone-line including a switch at a substation and a sig nal-lamp and source of current at a central station, of a subsidiary bridge or branch 01: the line adapted to form a local circuit for thelamp and source of current, and a relay connected with the line controlling the said bridge, as described.

3. The combination with a telephone-line having a switch in the line at the substation and a signal-lamp and a source of current in the line at the central station, of a re lay in the line and a bridge of the line in- 1 eluding a-n impedance-coil controlled thereby, as described.

4. The combination with a telephone-line of high resistance containing a source of current and connected with signal-lamps requiring for their operation current greater than the said source of current is able to produce in the line, of a subsidiary return-circuit of lower resistance and a relay controlled from the substation controlling the said subsidiary IO circuit, as described.

In Witness whereof Ihereunto subscribe my name this 1 1th day of September, A. D. 1895.

FRANK R. MCBERTY. Witnesses:

ELLA EDLER, LUCILE RUSSELL. 

